Chemical cementitious systems are a mixture of sand, cement, and proprietary chemicals (inorganic or organic), which when applied to masonry or concrete substrates provide a watertight substrate by chemical action. Proprietary chemicals are unique to each manufacturer, but typically include silicate and siloxane derivatives in combination with other chemicals. While the chemicals do not penetrate the substrate like the other cementitious systems, chemical systems also effectively become an integral part of the substrate after application.

Chemical cementitious systems, approximately 1 16-in thick, are thinner applications than other cementitious products. As with all cementitious systems, concrete or masonry substrates need not be dry for application. Chemical systems do not require curing, but capillary systems do.